#include<stdio.h>
// #include<stdlib.h>
// int clearInputBuffer(void){
//     int c;
//     while((c!=getchar())!='\n'&&c!=EOF){}
//     printf("Please re-enter\n");
//     printf("Please re-enter\n");
//     printf("Please re-enter\n");

//     return 0;
// }
int main()
{  
    double number1 = 0;
    double number2 = 0;
    char operation = 0;
//     char inputLine[100];
    

 loop_start:
   
    printf("Please enter an Arichmetic express.like this : 1 + 1 ");
    scanf("%lf %c %lf",&number1,&operation,&number2);
    // fgets(inputLine,sizeof(inputLine),stdin);
     //int scanfResult = scanf("%lf %c %lf",&number1,&operation,&number2);
    // int sscanfResult = sscanf(inputLine,"%lf %c %lf",&number1,&operation,&number2);
    
    // if(sscanfResult==3){
       
    switch (operation)
    {
    case '+':
        printf("=%lf\n",number1+number2);
        break;
    
    default:
        // printf("Iileal!\n");
        // printf("%d\n",sscanfResul);
        printf("Please re-enter\n");

        // clearInputBuffer();
        while(getchar()!='\n');
        goto loop_start;
        break;
    }
    // }else{
        // printf("Invalid input format!\n");
        //     printf("%d\n",scanfResult);
        // clearInputBuffer();
    
        // goto loop_start;
//     }
//     return 0;
    

// }
// #include<stdio.h>
// int main()
// {
//     int a=scanf("0");
    
//     printf("%d",a);

//     return 0;
}